Tamil Nadu Board of Secondary EducationHSC Science Class 12




  • Mendelism
  • Father of Genetics - Gregor Johann Mendel
  • Reasons for Mendel's success
  • Advantages of selecting pea plant for experiment by Mendel



The contribution of Mendel to Genetics is called Mendelism. It includes all concepts brought out by Mendel through his original research on plant hybridization. Mendelian genetic concepts are basic to modern genetics. Therefore, Mendel is called as Father of Genetics.


Gregor Johann Mendel:

Gregor Johann Mendel
(1822 – 1884)

  • Father of Genetics - Gregor Johann Mendel
  • The first Geneticist, Gregor Johann Mendel unraveled the mystery of heredity.
  • He was born on 22nd July 1822 in Heinzendorf Silesia (now Hyncice, Czechoslovakia), Austria.
  • After school education, later he studied botany, physics, and mathematics at the University of Vienna.
  • He then entered a monastery of St.Thomas at Brunn in Austria and continued his interest in plant hybridization.
  • In 1849, Mendel got a temporary position in a school as a teacher and he performed a series of elegant experiments with pea plants in his garden.
  • In 1856, he started his historic studies on pea plants.
  • 1856 to 1863 was the period of Mendel’s hybridization experiments on pea plants.
  • Mendel discovered the principles of heredity by studying the inheritance of seven pairs of contrasting traits of pea plants in his garden. Mendel crossed and catalogued 24,034 plants through many generations. His paper entitled “Experiments on Plant Hybrids” was presented and published in The Proceedings of the Brunn Society of Natural History in 1866.
  • Mendel was the first systematic researcher in the field of genetics.
  • Mendel worked on the rules of inheritance and arrived at the correct mechanism before any knowledge of cellular mechanism, DNA, genes, or chromosomes became available. Mendel insights and meticulous work into the mechanism of inheritance played an important role which led to the development of improved crop varieties and a revolution in crop hybridization.
  • Mendel died in 1884. In 1900 the work of Mendel’s experiments were rediscovered by three biologists, Hugo de Vries of Holland, Carl Correns of Germany, and Erich von Tschermak of Austria.


Mendel was successful because: 

  • He applied mathematics and statistical methods to biology and laws of probability to his breeding experiments.
  • He followed scientific methods and kept accurate and detailed records that include quantitative data of the outcome of his crosses.
  • His experiments were carefully planned and he used large samples.
  • The pairs of contrasting characters which were controlled by the factor (genes) were present on separate chromosomes.
  • The parents selected by Mendel were pure breed lines and the purity was tested by self-crossing the progeny for many generations.


Advantages of selecting pea plant for experiment by Mendel:

He chose the pea plant (Pisum sativum) because,

  • It is an annual plant and has clear contrasting characters that are controlled by a single gene separately.
  • Self-fertilization occurred under normal conditions in garden pea plants.
  • Mendel used both self-fertilization and cross-fertilization.
  • The flowers are large hence emasculation and pollination are very easy for hybridization.
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